1. Field of the Invention
The present invention relates to a utility pole.
In particular, the present invention relates to a utility pole, more in particular to a telecommunication pole, including a thermoplastic composite material, so as to said thermoplastic composite material.
Moreover, the present invention also relates to a process for manufacturing said utility pole.
2. Description of the Related Art
Electrical transmission wires, telephone wires and lighting installations are often supported on utility poles. Such poles must be capable of withstanding not only columnar load applied by the weight of the object supported thereon but also the bending load imposed by eccentric loading and by wind. As a general rule, wooden, concrete or steel poles have been used for this purposes. However, these poles present some disadvantages.
Wooden poles, for example, are subject to rot, i.e. to decomposition from the action of bacteria or fungi, and to pest attack, i.e. wood boreers and pecking fowl. Unfortunately, wooden poles are subjected to rot both at and below the ground surface which can result in a pole collapsing or toppling, sometimes without warning. To avoid this type of degradation, the wooden poles are usually treated with chemicals which are intended to protect and to prolong the useful life of the same. However, said chemicals may leach out of the poles so causing both a reduction of their protective ability and environmental problems. Moreover, the wooden poles are heavy and, consequently, their installation, in particular in inaccessible places, is difficult and expensive.
Steel poles are subject to rust and therefore need constant attention and maintenance. The rust proofing compounds normally used may also have a deleterious effect on the environment. Also steel poles are heavy and are not easily manipulated. Moreover, steel poles are electrically conductive and, even though extreme care may be taken to insulate the electrical installations from the poles, storm damages may result in the poles becoming electrified. Finally, also steel poles are expensive.
Concrete poles are even heavier than steel poles. As a result, the expenses of transporting and handling concrete poles may be excessive. They are, therefore, often constructed in fairly proximity to the installation site. Concrete poles, like the wooden and steel poles abovementioned, are subjected to environment damages, in particular concrete tends to crack as a consequence of temperature changes.
In order to overcomes all the above-mentioned disadvantages, fiber reinforced plastic (FRP) poles have been suggested in the prior art as an excellent replacement for wooden, steel and/or concrete poles.
For example, U.S. Pat. No. 4,803,819 relates to a reinforced hollow utility pole of thermoset fiber-reinforced resin, of substantially uniform overall cross-sectional dimension throughout its length, integrally-formed by the process of pultrusion. Said fiber reinforced resin consists essentially of a glass fiber reinforced resin system selected from the group consisting of isophthalic polyester, vinyl ester and epoxy. The abovementioned pole is said to have the following advantages:                it is formed in one piece to any desired length and it has a substantially uniform cross-section;        it is resistant to animal and insect damages and natural deterioration such as, for example rotting;        it is light and safe and allow the operators to install the same in a easier way and with a minimum hazard of possible short circuits.        
Moreover, the insulating properties, strength and resilience of the abovementioned pole make it safe against strikes by lightening and wind damages, thus preventing wide spread utility failure due to storms.
International Patent Application WO 01/022662 relates to an elongated support structure, suitable for outdoor use as a utility pole, post or piling, including an elongated core formed of a substantially homogeneous composite material and a reinforcing layer bonded to the outer surface of the core. The composite material from which the core is formed includes a matrix resin and a strengthening material of fine, elongated particles. The strengthening material intermixed with the resin is fibers of a length in a range of about 0.50-4.00 inches (12, 7-101 mm). Such fibrous material may be produced from wood shreds, coconut husks, palm bark, hemp, sisal, or bagasse from which substantially all moisture, resins and sap has been removed. The resin in which the strengthening material is mixed may be phenolic or polymeric resins that are cured by heat. The abovementioned elongated support structure is said to have many advantages such as, for example:                it reduces sources of chemical contamination in the environment;        it is economic to transport, to install and to maintain;        it is resistant to environmental degradation from rot, insect and weathering;        it has an enhanced resistance to failure under compressive and flexural loads.        
United States Patent Application US 2004/0228995 relates to a process for making a composite pole including the steps of shaping an integral mandrel in the form desired for the pole's interior and then applying a plurality of layers of reinforced composite material to the integral mandrel to form a pole including the composite material and the integral mandrel. A composite pole comprising an integral mandrel therein is also disclosed. The reinforced composite material includes a matrix component and a reinforcing component. The matrix component is a resinous material selected from epoxies, polyesters, acrylics, phenolics, or urea-formaldehyde resins which cure to form a bond with the reinforcing component. The reinforcing component is a fibrous material selected form fiberglass, aramid fibers, carbon fibers, or any other fibers which may be used for making fiber-reinforced plastics. The term fiber refer refers to a single homogeneous strand of material having a length of at least 5 mm, which can be spun into a yarn or roving, or made into a fabric. The use of a integral mandrel in making a pole simplifies the pole manufacture because it is not necessary to extract the reinforced composite tube from the mandrel. Moreover, for a given pole strength, less wall thickness is required and fewer layers of reinforced composite need to be applied.
However, the composite poles described above may still have some disadvantages.
For example, the composite poles above disclosed being made of cured composite materials are not easily recyclable at the end of their life. Moreover, the processes for manufacturing said composite poles (i.e. pultrusion or filament winding) are complex and have a slow production rate: consequently, productivity of the manufacturing plant is very low and, therefore, costs of the final products increase. Furthermore, said processes, in particular the filament winding process, require the use of solvents (for example, styrenic solvents) which, because of their toxicity, lead to risks for both the environment and the health of the operators.